This invention relates to a mixed analog/digital mixed integrated circuit wherein a circuit for processing of an analog signal and a circuit for processing of a digital signal are mixed or coexist.
A conventional analog/digital mixed integrated circuit has an analog unit which processes an analog signal inputted through an analog input signal line and converts the analog signal into a digital signal, a digital unit which is connected to the analog unit through a signal line and processes a digital signal, and a clock signal generator which supplies an analog unit operation clock signal for the analog unit and a clock signal for the digital unit.
In this circuit construction, the clock signal generator always generates the analog unit operation clock signal and the digital unit operation clock signal so that even when the analog unit is now processing an input signal, the digital unit, operation clock signal is always supplied to the digital unit for causing it to operate. For this reason, digital noise generated by the digital unit adversely affects the processing at the analog unit resulting in a problem of decreasing the accuracy of processing of the analog unit. In this case, when a signal is processed in the digital unit using a digital signal which has been converted at the analog unit having a decreased accuracy, certain corrections must be made. Moreover, the time required for making these correction becomes long as the number of analog/digital converted data increases.